fletcher



1. FLETCHER.

PERCUSSION ROCK DRILL..

AlPLlcATloN FILED MAR. 30. 191e.

' Patented June 3,1919.

2 SHEETS-SHEET l.

Il. FLETCHER.

PERCUSSION ROCK DRILL.

APPLICATION msn MAR. a0. me.

2 SHEETS-SHEET 2.

' Patnted June l3, 1919.v

JAMES ELETHEE, 0E NEWNES, NEW soU'rH WALES, AUSTRALIA.

PERCUSSION ROCK-DRILL.

Specification of Letters Patent.

Patented June 3, 1919.

Application led March 30, 1916. Serial No. 87,694.

'To all whom it may concern:

Be it known that I, JAMES FLETCHER, subject of the King of Great Britain and Ireland, residing at Newnes, New South vWales, Australia, have inventedcerta11i new and useful Improvements in Percussion Rock-Drills and Coal-Cutters Operated by Fluid-Pressure, of which the following is a specification.

This invention has been devised to improve drills of the 'type used for rock and coal holing, nicking, drilling, or wedging in respect vot the control of the plunger `action in drills operated by compressed air or steam for the purpose of effecting a change in the length of stroke of the plunger at the will of the operator and to providev for optional cushioning and also to enable the plunger to. be jigged on a short stroke for the purpose of relieving the cutting bit when it is'workin or jammed in a tight hole or channel, and a apting'the machine to be worked most eectively on high, medium, or low pressure air or' steam.

Intheaccompanying drawings, Figure 1 is a longitudinal section through the drill cylinder and valve chest; Fig. 2 is a half sectional ing with Fig. ,-l;

Fig. 3 is a transverse sectior on line ci-b Fig. l;

Fig. 4 is a half transverse section on line (1 -d Fig. l;

Fig. 5 is a transverse section on line e-f (Fig. 1) l Fig.- 6 1s a broken sectional elevation of manual control tube valve; and Fig. 6a a l transverse section through same;

Fig. 7 is a\fragment sectional elevation of portion of the main valve and of one head of the valve chamber; f d

Fig. 8 is an enlarged longitudinalsection through the main valve chamber and main valve; 1

Fig. 9 is a half top plan and horizontal section through .the main valve chamberand the main valve therein;

Fig. 10 is a transverse section taken at three dierent positions on Figs. 8 and 9..

The plunger head is shown in dotted position nearthe extreme outward end of its stroke in Fig. l.

The cylinder chamber communicates with the main valve through two'ports 22 a 23 located near)its rear and forward enig; A

plan correspondrespectively, the front port 23 being set a little backward from the extreme front end of the cylinder so as to insure the imprisonment of sulicien't air in front of the plunger head to partially cushion the same and prevent actual mechanical contact between the plunger `head and the cylinder end, a rubber ring buffer 82 being also fitted for this purpose.

The back port 22 mergesfdirectly into the aperture 25 on a plane face 27 on the side vof the cylinder, on which vplane ace the valve casing 26 is bolted down. The front end port 23 communicates with the aperture 28 on the face 27', through a cored passage 24. A by-pass 29 connects the cored passage 24 to the cylinder chamber at 30 through a plug cock or valve 3l, the stem of which is itted With a hand lever or other device for turning the. valve manually to open or close it as required. The aperture v30 enters the cylinder at a point rearward ofthe front end port 23 a distance slightly exceeding the length of the plunger head.

A -hole 32 is drilled through the Solid metal in the cylinder body parallel -with the cylinder axis, and thishole is placed in communication with the cylinder through iiveL by-pass holes, 33,34, 35, 36 and 37 located vpreferably as shown in Fig. 1.V

There may be a greateror less number oi' these by-pass holes, and they may be lo- 'cated differently from those shown in the drawing, but so as to operate simil-arly to those shown. The drilled hole 32- forms a seating for the manual control tube valve which is a neat t in it and is rotatable by means of a Spanner or hand lever enf gaged with its square stem end 38. This tube valve 90 has seven holes 39, 40, 41, 42,

. V43, 44 and 4 5 drilled through its wall. The

disposition of these sevenholes .at four angular positions isL shown in thedetail section Fig. 6a. The necessary number and respective positions of .the holes in the tubevalve'90 depend upon the number and disposition of the by-pass holes 33-37 through the cylinder wall. The inner end of the tube valve 90 is reduced in section lexternally as shown at 46, and holes `47 are made through the reduced part of itto act as passage-ways from its bore 48 into a passageway 49 which leads up' to the face '27.

A channel`50- is cut inthe face 27. At

either end this channel alines with holes 52 and 53 which are drilled radially through the wall of the valve chamber 26.

If the tube valve 90 is turned to any posid' tion in which one or more of the holes 39 to is not in alinement with one or more of the holes 33 to 37 in the cylinder wall, communication will not be established through any of the last mentioned series of holes to the passageways 52 and 53 leading through the wall of the valve chamber, but in any' of the four angular positions shown in Fig. 6a one or more of the holes 39 to 45 will come intoalinement with one or more of the holes 33 to 37 and establish communication through the hole or holes so brought into alinement between the interior of the cylinder and the said passageways 52, 53, leading into the valve chamber.

The action of the plunger will be governed by the adjustment of the valve 90, Fig. 6, in the way hereinafter described.

The valve chamber is cylindrical and the valve is of the usual multi-head piston type,

being the pressure inletand 61 the eX- haust outlet.

The inlet 6() (see Fig. 9) enters two annular spaces 62 and 63, and the exhaust 61 opens directly out of the central annular chamber 64. The main Jface ports 25 and 28 communicate with the cylinder ports 22 and 23 respectively and are respectively led into the annular cavities 65 and 66. The valve chamber is closed by solid covers 67 and 67x which are screwed home into its ends. In each of the covers is a small axial cylinder 68 68X in which the close fitting plun ers 69 69X on the ends of the valve stem 7() slide. Annular` grooves 71 and 71 are turned in each of the heads 67 and 67 and these grooves ,communicate through radial passages 72 and 72x with the cylinders 68 and 68x at the respective ends of the valve chamber.

It will'be noted on reference to Fig. 8

that the valve plunger .69 is home in its cylinder 68, and the passageways 72 open up f `hand end of Fig. 8) theplunger 69I .closes i the holes `v72?","and there is no longer communicationi fromv the end chamber 74 through the holes 72 ,fgroove 71X, passageways 53,

.50, 49,fandf tube j vaLlve 90 to the cylinder. 20.

y.The'rn'ainvvalveconsists of a central stem 70 lcarrying,'upon -it acentral head 75 and two Y groQYedheads'76 and 77 between saidcem w tralf'hefad 75, `'and ateither end, pluhgers 69 and v69". vrFrom the grooves in the headsl? 6 and 77, holesare drilled into the center of 4the stem and these* holes communicate by y the aan holes 79 .and so with the eylinders 681.68X in the valve chamber heads.

' Assuming that the valve is in the position shown in Figs. 1, 7 and 8, and that the manual control valve, Fig. 6, is turned so that the ports 39 and 42 therein aline with the ports 33 and 35, in the cylinder Wall; then the pressure service is opened so that the valve chamber` 62 and 63 contain air or steam under pressure. Said air or steam will pass from the chamber 62 to the chamber 65 and thence .through the face port 25 and the cylinder port 22 as shown by the arrows Figs. 1 and 8. Owing to the position of the valve, which as shownin the figures is in the extreme left position, pressure cannot pass Jfrom the chamber 63 to the cylinder port 23, but the forward end of the cylinder is open through said port 23, the passageway 24 and the tace port 28 and chamber 64 to the exhaust 61. Pressure acting on the back of the plunger will force it forward until its rear end passes the port 33. Thereupon 'pressure will pass through the said port 33 holes 72x being closed by the plunger 69X.

Pressure air or steam is however passed from the chamber 63 through the aXial hole 80 in the valve stem and internalI pressure is thus set up in the plunger cylinder 68X, and this pressure acts to keep the valve Ain the left-hand position as shown in Fig. 8.

.The air under pressure which has passed from the cylinder through the port 33 finds yegress however through the hole 52, owing to the fact that there is clearance around `the stem portion 81 of the valve which'carries the left hand head 69. AThis pressure acts against the grooved piston head 76 and overbalances .the pressure against the end of the right hand plunger 69", with the result 'that'V the valve is moved over to the right,

whereupon the passage 24 becomes open to pressure through the face port 28 and the chambers 66 and 63, and the port22 is opened to exhaust. The drill` plunger isy then retired backward by the pressure against its `lfront end, but as soon 'as its forward end left hand position. It -will be seen, there-- fore, that with this setting ofthe manual control tube valve 90, the drill plunger is reciprocated through a shortstrokein the back portion of the'cylinder 20. Similarly for any other setting of the tube valve 90 the length' of stroke permitted to the drill plunger and the position in which said -plunger may work in the cylinder is determined.

In the four working positions of the tube valve 90 the by-passes are opened in the fol` lowing groups viz.: No. 1, 33 and 35; No. 2, 34 and 35; No. 3, 34C; No. 4l, 36 and .37. In whichever direction the drill plunger is moving, its motion becomes reversed when it passes any one of the by-passes 33, 34, 35, 36, or 37 which is for the time being open through the tube valve 90.

rIhe cock 3l forms a short circuit from the hole 30 in the cylinder walll to the ressure and eduction passage 24C. By opening this cock, the pressure 'in the cylinder is short# circuited to the exhaust ,as soon as the plunger passes and so opens the aperture 30. In operating the machine, this valve is opened when the-drill is working against solid material, in which circumstances it is necessary to strike unyielding blows. When however soft or irregular material is being operated on, through `which the drill might at times break through rapidly, the cock 31 is closed. The piston cannot then overrun its stroke, vand strike the forward end of the cylinder.-

In' operating air orfsteam cradle drills of the percussive type it is known that the plunger moves in the cylinder' very rapidly and that when its forward movement is not arrested by the contact of the drill against solid rock the plunger frequently strikes the front end of the cylinder, and liability tol 4mechanical injury to the machine is thus always present, notwithstanding that some air cushioningl space is provided and notwithstanding also that buffer rings of rubber or like compressible substance are fitted to diminish the force of such accidental blows.

' In my invention reversal of the main valve is effected in suliicient time to admit air into the front end of the cylinder before the plunger has completed its stroke, the driving pressure behind the plunger escaping to exhaust at the same time as the pressure is admitted to the vfront end of the cylinder. The pressure in the front of the plunger in this case buffers it, but the machine does not strike its blows as solidly as is possible when the plunger is permitted to make its stroke without air buffering, The

. provision of the control .valve 31 in this invention gives the operator command of the machine so that he may adjust it by merely turning the valve 31 by a hand lever to operate with best 'efficiency under either working condition, that is to'say against a sohd unyieldingv face or in soft or irregular material. It is to be noted that the relief of air pressure from the front of the plunger-by short circuiting through the Valve 31 does not effect j reversal of the main valve by said by-passed air going through the holes 33, 34, 35, 36, or 37 and acting on the main valve, because the bypassed air is wire-drawn and finds a free exit through the' main port 42. By adjusting the valve 3l, any necessary degree of buifering may be provided for, and the operator therefore has adequate control so that he may suit the action of the drill to the particular conditions `in which it is j working.

the range of stroke of the plunger is fully controllable, as also vis the position in the cylinder in which a limitedlength of stroke is permitted to said plunger.

'Ihe two controls necessary to be manipulated by the operator to govern the stroke of the plunger and its reciprocating locus in the cylinder are the rotation of the tube valve 90 to an appropriate position to, connect up the required by-passes to the valve, reversing device, andthe adjustment of the valve 31 in full open, full closed, or partially openposition. E Heretoforeone pair of byfpasses has been provided to convey' pressure air from either end of the cylinder to the valve operating device, but with only one pair of by-passes the stroke. of the plunger is always identical, and it is not practicable for the operator to vary the length ofthe stroke or to jig the plunger for the purpose of loosening the drill when the same is fouled or jammed.

What I claim as'my invention and desire. to secureV by Letters Patent is ioo l. In a device of the character described,

the combination of a valve casing, a cylinder connected to said casing, said cylinder having a series of by-pas's openings through its wall and also having a passage therein leadingl from the forward portion of said cylinder to said casing, there being a bypass intermediate the ends of said passage .between the latter vand the interior of the of by-pass openings through its wall, said openings being spaced 'unequal distances apart, a valve havinga series of angularly disposed ports Ia plurality of which is adapted to aline simultaneously with a plurality of said by-pass openings respectively, and a valve casing connected to said cylinder and adapted to communicate therewith through said valve.

3. In a device of the character described,

the combination of a cylinder having a series of bypass openings through its Wall, 'said openings being spaced unequal distances apart, a tube valve having a series of angularly disposed ports a plurality of which is adapted to simultaneously aline with a plurality of said by-pass openings r spectively and a valve casing connected to said cylinder, there being a passage from the end' of. said tube valve through the cylinder Wall to establish communication between the cylinder and valve casing.

In testimony whereof- I have aixed my signature in presence of two Witnesses.

JAMES 'FLETCHER Witnesses:

D. G. RUSSELL', W. I. Davis. 

